A rose by any other name is still a 0.8

In the “wild,” IRT scores are typically on the standard normal metric, meaning that bell-shaped distribution when it has a mean of 0 and a standard deviation of 1. Due to SCIENCE!, we know that almost all of the scores in such a distribution will fall between -3 (well below average) and +3 (well above average) with a lot of the scores piling up closer to 0. For statistics-minded folks, this distribution is pretty familiar and easy to interpret (You … Read More

Computerized Adaptive Testing

  Computerized adaptive testing (CAT1) refers to the procedures underlying a test/assessment/whatevs that is generated “on the fly” by a computer, using a person’s previous answers to determine what question the person will see next. My amazing, trade-mark infringing, artwork notwithstanding, CAT is not magic – it is, in fact, SCIENCE! A reader-friendly conceptual overview of CAT was recently published here: https://www.ispor.org/ValueOutcomesSpotlight (paywall warning!). I’ll wait while you go read that… Finished? Great! OK – so now we know that … Read More

Comparing Average Level and Within-person Consistency in Clinical Disability Using AVP-825 vs. Sumatriptan Tablets: Applying Location Scale Mixed-effects Models

Shulman, K., McGinley, J. S., Wirth, R. J., Buse, D. C., and Lipton, R. L. (2017). Comparing Average Level and Within-person Consistency in Clinical Disability Using AVP-825 vs. Sumatriptan Tablets: Applying Location Scale Mixed-effects Models. Poster to be presented at the 2017 American Academy of Neurology (AAN). Boston, MA.